This invention relates to supercritical fluid extraction.
In supercritical fluid extraction, an extraction vessel is held at a temperature above the critical point and is supplied with fluid at a pressure above the critical pressure. Under these conditions the fluid within the extraction vessel is a supercritical fluid. In one type of apparatus for supercritical extraction, there is a specially constructed extraction vessel within a source of heat.
A prior art apparatus for supercritical extraction of this type is described by B. W. Wright, et. al., in ANAL. CHEM. 59, 38-44 (January 1987) using a glass-lined extraction chamber within a bolted stainless steel extraction vessel heated in an oven. This type of extraction apparatus has the disadvantages of: (1) requiring time consuming steps to open the pressurized extraction vessel before use to insert the sample and again to open it after use to remove the spent sample; and (2) under some circumstances, requiring the handling of a hot extraction vessel.